Interactive Effects of HIV Infection and Cannabis Use on Insula Subregion Functional Connectivity.

Chronic inflammation in the central nervous system is one mechanism through which human immunodeficiency virus (HIV) may lead to progressive cognitive decline. Given cannabis's (CB's) anti-inflammatory properties, use prevalence among people living with HIV (PLWH), and evidence implicating the insula in both, we examined independent and interactive effects of HIV and CB on insular circuitry, cognition, and immune function. We assessed resting-state functional connectivity (rsFC) of three insula subregions among 106 participants across four groups (co-occurring: HIV+/CB+; HIV-only: HIV+/CB-; CB-only: HIV-/CB+; controls: HIV-/CB-). Participants completed a neurocognitive battery assessing functioning across multiple domains and self-reported somatic complaints. Blood samples quantified immune function (T-cell counts) and inflammation (tumor necrosis factor alpha [TNF-α]). We observed interactive HIV × CB effects on rsFC strength between two anterior insula (aI) subregions and sensorimotor cortices such that, CB appeared to normalize altered rsFC among non-using PLWH. Specifically, compared to controls, HIV-only and CB-only groups displayed decreased dorsal anterior insula (DI) - postcentral gyrus rsFC and increased ventral anterior insula (VI) - supplementary motor area rsFC, whereas the co-occurring group displayed DI and VI rsFC more akin to that of controls. Altered DI - postcentral rsFC correlated with decreased processing speed and somatic complaints, but did not significantly correlate with inflammation (TNF-α). These outcomes implicate insula - sensorimotor neurocircuitries in HIV and CB and are consistent with prior work suggesting that CB use may normalize insula functioning among PLWH.